count() doesnt send the mapper to get_bind()

[Mike Bayer]

no solution at this time as we pass literal_column('*') in, which can't be related to the mapper directly. we can add parententity to it, but it still is not a FROM. new state would need to be added to Query.

[Mike Bayer]

see also #3242

[Mike Bayer]

diff --git a/lib/sqlalchemy/orm/persistence.py b/lib/sqlalchemy/orm/persistence.py
index f477e1d..9595755 100644
--- a/lib/sqlalchemy/orm/persistence.py
+++ b/lib/sqlalchemy/orm/persistence.py
@@ -1120,7 +1120,7 @@ class BulkUpdate(BulkUD):
         super(BulkUpdate, self).__init__(query)
         self.query._no_select_modifiers("update")
         self.values = values
-        self.mapper = self.query._mapper_zero_or_none()
+        self.mapper = self.query._bind_mapper()

     @classmethod
     def factory(cls, query, synchronize_session, values):
diff --git a/lib/sqlalchemy/orm/query.py b/lib/sqlalchemy/orm/query.py
index d2bdf5a..f5f04e1 100644
--- a/lib/sqlalchemy/orm/query.py
+++ b/lib/sqlalchemy/orm/query.py
@@ -160,7 +160,6 @@ class Query(object):

         for from_obj in obj:
             info = inspect(from_obj)
-
             if hasattr(info, 'mapper') and \
                     (info.is_mapper or info.is_aliased_class):
                 self._select_from_entity = from_obj
@@ -286,8 +285,9 @@ class Query(object):
         return self._entities[0]

     def _mapper_zero(self):
-        return self._select_from_entity or \
-            self._entity_zero().entity_zero
+        return self._select_from_entity \
+            if self._select_from_entity is not None \
+            else self._entity_zero().entity_zero

     @property
     def _mapper_entities(self):
@@ -301,11 +301,14 @@ class Query(object):
             self._mapper_zero()
         )

-    def _mapper_zero_or_none(self):
-        if self._primary_entity:
-            return self._primary_entity.mapper
-        else:
-            return None
+    def _bind_mapper(self):
+        ezero = self._mapper_zero()
+        if ezero is not None:
+            insp = inspect(ezero)
+            if hasattr(insp, 'mapper'):
+                return insp.mapper
+
+        return None

     def _only_mapper_zero(self, rationale=None):
         if len(self._entities) > 1:
@@ -988,6 +991,7 @@ class Query(object):
             statement.correlate(None)
         q = self._from_selectable(fromclause)
         q._enable_single_crit = False
+        q._select_from_entity = self._mapper_zero()
         if entities:
             q._set_entities(entities)
         return q
@@ -2526,7 +2530,7 @@ class Query(object):

     def _execute_and_instances(self, querycontext):
         conn = self._connection_from_session(
-            mapper=self._mapper_zero_or_none(),
+            mapper=self._bind_mapper(),
             clause=querycontext.statement,
             close_with_result=True)

[Mike Bayer]

note that this patch also sends the bind mapper through for regular column-based queries, which is a good thing. add tests for all that.

[Mike Bayer]

see also #1326

[Mike Bayer]

this patch fixes both, by separating out the entities into those where we want the "froms" vs. those that we just want "entity zero":

diff --git a/lib/sqlalchemy/orm/persistence.py b/lib/sqlalchemy/orm/persistence.py
index f477e1d..9595755 100644
--- a/lib/sqlalchemy/orm/persistence.py
+++ b/lib/sqlalchemy/orm/persistence.py
@@ -1120,7 +1120,7 @@ class BulkUpdate(BulkUD):
         super(BulkUpdate, self).__init__(query)
         self.query._no_select_modifiers("update")
         self.values = values
-        self.mapper = self.query._mapper_zero_or_none()
+        self.mapper = self.query._bind_mapper()

     @classmethod
     def factory(cls, query, synchronize_session, values):
diff --git a/lib/sqlalchemy/orm/query.py b/lib/sqlalchemy/orm/query.py
index d2bdf5a..2ea5dd2 100644
--- a/lib/sqlalchemy/orm/query.py
+++ b/lib/sqlalchemy/orm/query.py
@@ -146,7 +146,7 @@ class Query(object):
                         ext_info,
                         aliased_adapter
                     )
-                ent.setup_entity(*d[entity])
+                ent.setup_entity(entity, *d[entity])

     def _mapper_loads_polymorphically_with(self, mapper, adapter):
         for m2 in mapper._with_polymorphic_mappers or [mapper]:
@@ -160,7 +160,6 @@ class Query(object):

         for from_obj in obj:
             info = inspect(from_obj)
-
             if hasattr(info, 'mapper') and \
                     (info.is_mapper or info.is_aliased_class):
                 self._select_from_entity = from_obj
@@ -286,8 +285,9 @@ class Query(object):
         return self._entities[0]

     def _mapper_zero(self):
-        return self._select_from_entity or \
-            self._entity_zero().entity_zero
+        return self._select_from_entity \
+            if self._select_from_entity is not None \
+            else self._entity_zero().entity_zero

     @property
     def _mapper_entities(self):
@@ -301,11 +301,14 @@ class Query(object):
             self._mapper_zero()
         )

-    def _mapper_zero_or_none(self):
-        if self._primary_entity:
-            return self._primary_entity.mapper
-        else:
-            return None
+    def _bind_mapper(self):
+        ezero = self._mapper_zero()
+        if ezero is not None:
+            insp = inspect(ezero)
+            if hasattr(insp, 'mapper'):
+                return insp.mapper
+
+        return None

     def _only_mapper_zero(self, rationale=None):
         if len(self._entities) > 1:
@@ -988,6 +991,7 @@ class Query(object):
             statement.correlate(None)
         q = self._from_selectable(fromclause)
         q._enable_single_crit = False
+        q._select_from_entity = self._mapper_zero()
         if entities:
             q._set_entities(entities)
         return q
@@ -2526,7 +2530,7 @@ class Query(object):

     def _execute_and_instances(self, querycontext):
         conn = self._connection_from_session(
-            mapper=self._mapper_zero_or_none(),
+            mapper=self._bind_mapper(),
             clause=querycontext.statement,
             close_with_result=True)

@@ -3160,7 +3164,7 @@ class _MapperEntity(_QueryEntity):

     supports_single_entity = True

-    def setup_entity(self, ext_info, aliased_adapter):
+    def setup_entity(self, original_entity, ext_info, aliased_adapter):
         self.mapper = ext_info.mapper
         self.aliased_adapter = aliased_adapter
         self.selectable = ext_info.selectable
@@ -3507,9 +3511,9 @@ class _BundleEntity(_QueryEntity):
         for ent in self._entities:
             ent.adapt_to_selectable(c, sel)

-    def setup_entity(self, ext_info, aliased_adapter):
+    def setup_entity(self, original_entity, ext_info, aliased_adapter):
         for ent in self._entities:
-            ent.setup_entity(ext_info, aliased_adapter)
+            ent.setup_entity(original_entity, ext_info, aliased_adapter)

     def setup_context(self, query, context):
         for ent in self._entities:
@@ -3553,6 +3557,7 @@ class _ColumnEntity(_QueryEntity):
                 _ColumnEntity(query, c, namespace=column)
             else:
                 return
+
         elif isinstance(column, Bundle):
             _BundleEntity(query, column)
             return
@@ -3592,15 +3597,23 @@ class _ColumnEntity(_QueryEntity):
         # leaking out their entities into the main select construct
         self.actual_froms = actual_froms = set(column._from_objects)

-        self.entities = util.OrderedSet(
-            elem._annotations['parententity']
-            for elem in visitors.iterate(column, {})
+        all_elements = [
+            elem for elem in visitors.iterate(column, {})
             if 'parententity' in elem._annotations
-            and actual_froms.intersection(elem._from_objects)
+        ]
+
+        self.entities = util.unique_list([
+            elem._annotations['parententity']
+            for elem in all_elements
+        ])
+        self._from_entities = set(
+            elem._annotations['parententity']
+            for elem in all_elements
+            if actual_froms.intersection(elem._from_objects)
         )

         if self.entities:
-            self.entity_zero = list(self.entities)[0]
+            self.entity_zero = self.entities[0]
         elif self.namespace is not None:
             self.entity_zero = self.namespace
         else:
@@ -3623,10 +3636,12 @@ class _ColumnEntity(_QueryEntity):
         c.entity_zero = self.entity_zero
         c.entities = self.entities

-    def setup_entity(self, ext_info, aliased_adapter):
+    def setup_entity(self, original_entity, ext_info, aliased_adapter):
         if 'selectable' not in self.__dict__:
             self.selectable = ext_info.selectable
-        self.froms.add(ext_info.selectable)
+
+        if original_entity in self._from_entities:
+            self.froms.add(ext_info.selectable)

     def corresponds_to(self, entity):
         # TODO: just returning False here,

[Mike Bayer]

• The primary :class:.Mapper of a :class:.Query is now passed to the :meth:.Session.get_bind method when calling upon :meth:.Query.count, :meth:.Query.update, :meth:.Query.delete, as well as queries against mapped columns, :obj:.column_property objects, and SQL functions and expressions derived from mapped columns. This allows sessions that rely upon either customized :meth:.Session.get_bind schemes or "bound" metadata to work in all relevant cases. fixes #3227 fixes #3242 fixes #1326

→ <<cset 611883ffb35c>>